title: Simple and rapid data-reduction method with pixel-level spatial frequency of shift-rotation method.
abstract: Absolute testing methods are commonly employed in surface metrology to calibrate the reference surface deviation and obtain the absolute deviation of the surface under test. A simple and reliable data-reduction method of absolute shift-rotation method with rotational and translational measurements is presented here, which relies on the decomposition of the surface deviation into rotationally asymmetric and symmetric components. The rotationally asymmetric surface deviation can be simply obtained by classical N-position averaging method. After that, the two-dimensional problem of estimating the other rotationally symmetric surface deviation can be simplified to a one-dimensional problem, and it can be directly calculated out with pixel-level spatial frequency based on several measurements of different translations in one same direction. Since that no orthogonal polynomials fitting, such as Zernike polynomials, is required in the calculation, the data reduction of the method is simple and rapid. Experimental absolute results of spherical surfaces are given.
authors.forename: W
authors.initials: W
authors.lastname: Song
authors.forename: X
authors.initials: X
authors.lastname: Hou
authors.forename: F
authors.initials: F
authors.lastname: Wu
authors.forename: Y
authors.initials: Y
authors.lastname: Wan